That's a freaking lot of tier 4 people in FR.
Yes it's one of the major issues of the setting; you can't throw a rock without the risk of hitting an archmage. The role of the individual player characters are often overshadowed by the real movers and shakers, who shuffle you around like pieces on a gameboard, while they are engaged in a long-running magical cold war. Elminster describes this state of affairs in the novel
Spellfire where, if, say, he and Manshoon decided to tap all their power sources, allies, clones, simulacrums, et. al., the entire continent would likely be destroyed. So they don't use their full power for fear of mutual annihlation.
And since many heroes of the Realms have become iconic characters, important to the brand,
they don't often die, and continue to lurk about even as the timeline skips ahead to justify changes for each new edition.
When
Tomb of Annihlation came around, with Acererak deciding to use the Realms as the location for his latest scheme, my response was "good luck with that". Even if the player characters bungle it up, there's characters just as powerful as the Demilich already there!
For example, Larloch the Shadow King, who as I recall was level 32 in 3.x, and could easily take over the world- but he'd rather focus on learning more about magic than actually bother, so he most just sits around and studies, lol.
